The Biomedical Informatics Research Network (BIRN) is a recently-launched initiative to foster large-scale collaborations in biomedical science by utilizing the capabilities of the emerging national cyberinfrastructure (high speed networks, distributed high-performance computing and the necessary software integrative capabilities). Scientists at the San Diego Supercomputer Center and the School of Medicine at the University of California San Diego (UCSD) serve as the BIRN Coordinating Center (BIRN CC) for this large project. The BIRN CC serves the critical task of developing, deploying and maintaining key infrastructure components, including high bandwidth connectivity via Internet 2, Grid-based security, file management and computational services, techniques to federate databases and shared visualization and analysis environments. In its initial phase, the BIRN involves a consortium of 12 universities participating in test bed projects centered around brain imaging of human neurological disorders and associated animal models. Groups are working on large scale, cross-institutional imaging studies on Alzheimer's disease, depression and schizophrenia using structural and function MRI. Others are studying animal models relevant to the study of multiple sclerosis, attention deficit disorder, Parkinson's disease and brain cancer using MRI, whole brain histology and high-resolution light and electron microscopy. The BIRN CC provides the focal point for interactions among the BIRN partner sites, both coordinating and catalyzing the successful collaboration of a large group of highly talented scientists. This proposal describes continuation plans for the BIRN CC for the next five years. In the next phase, the BIRN CC will continue to support and enhance the existing infrastructure while fostering and facilitating collaboration among the BIRN participants. Development and implementation of new technologies will continue to be tightly coupled to the requirements of the various test bed projects and will be informed by lessons learned during the initial phase. At the same time, the BIRN infrastructure will continue to evolve in accordance with emerging Grid standards, anticipating the longevity and future expansion of the BIRN.